Conventionally, an inboard engine (inboard engine-outboard drive) in which an engine is arranged inside a hull and power is transmitted to an outdrive device arranged outside the hull is known (for example, see the Patent Literature 1). The outdrive device is a propulsion device propelling the hull by rotating a screw propeller. The outdrive device is also a rudder device which is rotated concerning a traveling direction of the hull so as to turn the hull.
In addition to the outdrive device, a ship steering system for the outdrive device has a control device instructing a rotation direction of the outdrive device and an operation lever instructing a traveling direction of a hull to a control device. The ship steering system for the outdrive device has a calibration function for adjusting an actual traveling direction to the traveling direction of the hull instructed by the operation lever. Work adjusting the actual traveling direction to the traveling direction of the hull instructed by the operation lever is referred to as calibration work.